Flashlamp

ABSTRACT

A percussively ignited flashlamp is described, in which a glass envelope containing a filling of combustible material, such as zirconium shreds, and a combustion-supporting gas, such as oxygen terminates at one end in a press seal, through which a hollow metal tube extends, the tube being closed at its outside end and open at its inside end, and filled with percussive material. A wire can extend into the combustible material in the tube.

United States Patent Inventor Bernard Kopelman Salem, Mass. App]. No. 679,142 Filed Oct. 30, 1967 Patented June 15, 1971 Assignee Sylvania Electric Products Inc.

FLASHLAMP 4 Claims, 2 Drawing Figs.

US. Cl 431/93 Int. Cl F211: 5/02 Field of Search 431/92, 93,

[ 56] References Cited UNITED STATES PATENTS 3,384,441 5/1968 Fink et al 431/95 FOREIGN PATENTS 431,953 7/1935 Great Britain 431/93 Primary Examiner-Charles J. Myhre Attorneys-Norman J. OMalley and Laurence Burns ABSTRACT: A percussively ignited flashlamp is described, in which a glass envelope containing a filling of combustible material, such as zirconium shreds, and a combustion-supporting gas, such as oxygen terminates at one end in a press seal, through which a hollow metal tube extends, the tube being closed at its outside end and open at its inside end, and filled with percussive material. A wire can extend into the combustible material in the tube.

PATENTEU JUN] 519m BERNARD KOPELMAN INVENTOR ATTORNEY FLASHLAMP FIELD or INVENTION BRIEF DISCUSSION OF PRIOR ART Percussively ignited flashlamps have many advantages over prior flashlamps which use a heated electrical filament to ignite the combustible material. The need for the filament is eliminated as well as the electrical battery and its accompanying circuitry. At thesame time, when the lamp is used for illuminating an object for photography, the possibility of the loss of a picture by failure of the battery to ignite the lamp is eliminated. The battery often becomes dead when the camera is unused for a while, and a picture can be lost if the photographer doesn't notice this until the failure of the lamp to ignite.

Such a flashlamp is shown in my copending US. Pat. application Ser. No. 667,195 filed Sept. 12, 1967 for a Flashlamp. In that application, a flashlamp suitable for setting off by a blow directed against the side of a metal tube extending from a glass bulb is shown.

BRIEFSUMMARY OF INVENTION The present invention relates to an improvement of the device of the application mentioned above. We have discovered that the glass envelope enclosing the combustible fill can have a pressed seal with the hollow metal tube sealed therethrough in a manner similar to that of a lead-in wire.

This construction allows the flashlamp to be, for the most part, made on the same machinery now used for making electrically ignited flashlamps of the pressedseal type, thereby avoiding the necessity for expenditure of tremendous sums for new machinery to make percussive flashlamps. Moreover, the long length of seal insures that the percussive tube is firmly sealed to the glass. This is important, because it insures a long shelf life to the lamp and thereby improves the reliability of the device.

In manufacture, a hollow tube of suitable metal is sealed through the softened glass in the same manner as alead-in wire would be, the glass being pressed around it into a flat portion extending from' a glass tube whose other end is open. Care should be taken to keep from collapsing the tube. Powdered percussive material can then be placed in the metal tube through its open end and the open end of the glass tube, either by being forced into it through a hypodermic needle, or by placing a wire coated with the material into the metal tube. The wire can be left in the tube if desired, or it can be removed after filling the metal tube with the percussive mixture. If it remains in the tube it can act as an anvil against which the percussive material is pressed for detonation.

After filling the metal tube, the glass tube is filled with combustible material, such as shredded zirconium foil, and oxygen, and the open end sealed. The lamp, can, of course, be made in any other suitable manner.

In operation, the metal tube can be placed against an anvil, say a portion of a plastic base as in my copending application Serial No. 667,195, and a blow struck against the side of the metal tube, compressing it against the anvil.

The metal tube can be of copper, which being a soft metal,

is readily deformed by a blow for detonation. It may also be of any other suitable metal, for example, a nickel-chrome alloy such as the well-known No. 4 Alloy. The glass can be of a typre suitable for sealing to the metal used.

he diameter of the lamp tube or bulb will generally be small, say about 0.35 inch, and the diameter of the metal tube about 0.040 inch. The wire in the tube, if used, will of course be smaller than the inside diameter of the metal tube, which is about 0.032 inch. The wire in such a case can be about 0.020 inch in diameter. The above sizes are given to show the very small dimensions of the flashlamp and the metal tube which are convenient for many photographic uses. Other sizes can be used where desired.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects features and advantages of the invention will be apparent from the following specification, taken in connection with the accompanying drawing, in which:

FIG. 1 is an elevational view of a lamp according to the invention; and

FIG. 2 is an enlarged view of the base showing the percussive portion of the lamp.

In FIG. 1, the glass envelope 1 is in the form of a tube sometimes herein called a bulb" having the sealed exhaust tubulation 2 at one end and the flatly pressed portion 3 extending from the other end. The hollow metal tube 4, shown enlarged in FIG. 2, extends through the flatly pressed portion 3 and its outside end 5 is sealed by crimping, welding, soldering or the like. A high temperature solder such as silver solder can be used. The wire 6 is placed in hollow tube 4, leaving space between the two for the percussive mixture, which can be, for example, the mixture shown in application Ser. No. 667,195. The wire 6 is preferably of hard material such as steel and can extend out of the hollow tube 4 into the interior of envelope 1 through the open end 7 of metal tube 4 inside the envelope 1.

A filling of shredded zirconium foil or some other suitable combustible material is present in the envelope 1, in the usual flashlamp manner, together with a filling of a combustion-supporting gas such as oxygen, at a high pressure, say 5 atmospheres or even more.

From the foregoing specification various modifications will be apparent to a worker skilled in the art, without departing from the spirit and scope of the invention, which is set forth in the claims.

The percussive material 8 should be as little as necessary for ignition of the zirconium shreds, and about 1 milligram was found satisfactory in the small lamp described. The amount used extended about halfway up the tube 4. The upper end of tube 4 preferably extends to a position near the middle of the filling of zirconium shreds 9 to prevent blowing all the shreds toward the tip of the bulb on detonation.

The use of a wire 6 in the metal tube 4 serves also to keep the tube open after the blow that sets it off, thus preventing blowout at the bottom of the tube. The wire 6 is held in the tube by the percussive material.

What I claim is:

l. A flash lamp comprising an enclosing light-transmitting envelope, a filling of combustible material therein, a filling of combustion-supporting gas therein, said envelope having a pressed seal at one end thereof, a hollow metal tube extending hermetically through said pressed seal, said tube being closed at its outside end and open at the end inside the envelope, and a filling of percussive material in said tube.

2. The lamp of claim 1, in which the hollow metal tube is soft enough to deform under impact and detonate the device.

3. The lamp of claim 1, in which the envelope is of glass.

4. The lamp of claim 1, and a wire extending into the metal tube. 

1. A flash lamp comprising an enclosing light-transmitting envelope, a filling of combustible material therein, a filling of combustion-supporting gas therein, said envelope having a pressed seal at one end thereof, a hollow metal tube extending hermetically through said pressed seal, said tube being closed at its outside end and open at the end inside the envelope, and a filling of percussive material in said tube.
 2. The lamp of claim 1, in which the hollow metal tube is soft enough to deform under Impact and detonate the device.
 3. The lamp of claim 1, in which the envelope is of glass.
 4. The lamp of claim 1, and a wire extending into the metal tube. 